1. Field of the Invention
This invention relates to hoists used in building concrete walls and in particular to a wall climbing form hoist for handling form units in the construction of concrete wall structures for multi-story buildings.
2. Background of the Prior Art
In the construction of a multi-story building, such as an office building, apartment building and the like, these buildings may have thirty or more floors. Where concrete is used in the construction of the outside or inside walls, it is necessary to provide cranes in the setting up and then stripping of the forms from a set wall panel for reuse in continuing the completion of the wall. Unless a crane is available as required in the setting up and stripping of the forms the wall not only becomes costly, but additional cost increases are incurred by lost time on other operations, that must be performed on a meshing or synchronized time schedule with the wall forming operation. It is apparent also that appreciable down time of the crane may take place, when it could be more efficiently utilized on other jobs at the building site. Where open crane time for timely handling of the form units is not available, construction usually proceeds behind schedule with resultant monetary losses. In some instances, the size of the building being constructed relative to the building site may preclude the use of a crane.
A system for constructing concrete walls about two stories high is shown in U.S. Pat. No. 2,516,318; and for multi-story buildings, in U.S. Pat. Nos. 4,043,087; and 2,118,374. Self-lifting form systems now in use are generally cumbersome and, although inconvenient to manipulate during both a wall climbing operation and a form handling operation, have been found to be generally satisfactory. U.S. Pat. No. 3,628,223 discloses a climbing form hoist that includes a telescopic mast comprised of a pair of vertical lower mast sections for telescopically receiving associated upper mast sections which are extended and retracted by a common reversible electric motor. The upper mast sections carry an outer form unit. With the mast retracted and attached at its lower end to a completed lower wall section, the inner and outer form units are braced or tied together in any well-known manner after which a new lift or wall section is poured. When the new pour has set, the outer form unit, after being stripped from the wall structure, is elevated by the extension of the upper mast sections to a new pour position wherein its lower end is attachable to the previously poured wall section. The lower mast sections are then released from the wall, the upper mast section is retracted and the lower mast section again connected to the wall. The inner form unit is then repositioned for another lift to be poured.
U.S. Pat. No. 4,290,576 discloses a climbing scaffolding which utilizes a guiding rail only as a vertical guide, but not to support the load resulting from the weight of the scaffolding in the vertical direction. The ""576 patent requires its operators to manually fix the scaffolding in its lifted position by inserting pins into cutouts or by placing wedges underneath to support the load. U.S. Pat. No. 5,000,287 discloses a displaceable platform which is movable sectionwise on a wall, comprising support shoes, carrying rails, and a bracketing arrangement to support the platform. The thrust of the ""287 patent is the correction of non-uniform upward travel of its displacement elements through very small advancements on a toothed displacement rack and a common drive and controller apparatus that prohibits further upward displacement until all linear drives have completed the preceding working step or one of the proceeding working steps. While the ratcheting mechanism of the ""287 patent""s tooth displacement rack may provide for fewer incidents of jamming, therefore minimizing related down time due to mechanical failures, the construct of the present invention is designed such that the platform will move in a substantially level manner without the need to correct the movement along one rail while fixing the position of the platform along another rail.
U.S. Pat. No. 5,630,482 discloses a self-climbing device which utilizes two types of scaffolding shoes: one for guiding and one for guiding and exhibiting attachment devices; two types climbing heads: a lower head with a pivotable member supported by a sidewall enclosure, and an upper head with a pivotable member supported by two additional housing walls provided between the outer housing walls of the sidewall enclosure; and two types of protuberances extending from a guide rail which provide, in a plurality of steps, a locking and loosening means by which a platform may be lifted or lowered along the length of a mounting rail. The present invention alleviates much of the complexity of the ""482 patent by providing a simplified means for alternately supporting the wall climbing form hoist and moving the mounting rail or mast by utilizing one type of mounting support and a simplified mounting rail or mast.
the wall climbing form hoist of the present invention provides for an appreciable reduction both in the amount of labor and crane time required in the construction of multistory outside or inside concrete walls (for example interior core shafts like stairwells and elevator shafts). The hoist is efficient in operation to handle both the inside and the outside form units for the pouring and setting of successive lifts or horizontal wall sections and is readily adapted for handling form gangs. The hoist is hydraulically operated and remotely controlled and includes a platform or scaffold upon which workmen can be safely carried. A base or supporting frame carries the platform and the outer form unit. A pair of masts are releasably secured to a lower section of the poured concrete wall and movably carried on the base frame for relative up and down movement by a hydraulic cylinder and a pair of ratcheting dog latch assemblies, a movement much like that undertaken in the operation of a common car jack, where a human arm provides a force like that of a hydraulic cylinder on a ratcheting means which displaces a vehicle while preventing the reversal of such a displacement.
With the first two stories of the concrete wall structure previously constructed in any suitable manner, two pair of mounting supports are secured to the poured wall sections and the hoist is lifted in position by a crane or suitable alternative means to provide for the securement of the masts to the wall and the setting of the outer form unit and an inner form unit for a new pour. When the new pour has set, the support frame is supported on the upper mounting supports and the hydraulic cylinder and latch dog assemblies are used to move the masts upwardly a story height. The support frame is moved upwardly relative to the masts to locate the form unit in a next pour position wherein the lower end thereof is attached to a base sill secured to the set pour. A new pour is then made and the cycle of operations repeated until a desired height of the wall structure is attained. A further advantage of the invention is its ability to overcome uneven sections of poured wall through the utilization of shims mountable when necessary between the wall and the wall mounting assemblies. In an embodiment of the invention, linear activators are positioned such that the base frame and.masts are manipulated to lower the climbing form hoist a distance equal to the length of its ascent path, or a portion thereof. In another embodiment of the invention a crane is utilized to lower the climbing form hoist to the ground.